Kerberos Working Group L. Zhu
Internet-Draft Microsoft Corporation
-Updates: 4120 (if approved) S. Hartman
+Updates: 4120 (if approved) S. Hartman
Intended status: Standards Track MIT
Expires: September 6, 2007 March 5, 2007
- A Generalized Framework for Kerberos Pre-Authentication
- draft-ietf-krb-wg-preauth-framework-05
+ A Generalized Framework for Kerberos Pre-Authentication
+ draft-ietf-krb-wg-preauth-framework-05
Status of this Memo
By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes
- aware will be disclosed, in accordance with Section 6 of BCP 79.
+ aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
@@ -156,10 +28,10 @@ Status of this Memo
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
- http://www.ietf.org/ietf/1id-abstracts.txt.
+ http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
- http://www.ietf.org/shadow.html.
+ http://www.ietf.org/shadow.html.
This Internet-Draft will expire on September 6, 2007.
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mechanisms. The model describes what state in the Kerberos request a
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Table of Contents
- 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
- 2. Conventions and Terminologies Used in This Document . . . . . 5
- 3. Model for Pre-Authentication . . . . . . . . . . . . . . . . . 5
- 3.1. Information Managed by the Pre-authentication Model . . . 6
- 3.2. Initial Pre-authentication Required Error . . . . . . . . 8
- 3.3. Client to KDC . . . . . . . . . . . . . . . . . . . . . . 9
- 3.4. KDC to Client . . . . . . . . . . . . . . . . . . . . . . 10
- 4. Pre-Authentication Facilities . . . . . . . . . . . . . . . . 10
- 4.1. Client-authentication Facility . . . . . . . . . . . . . . 12
- 4.2. Strengthening-reply-key Facility . . . . . . . . . . . . . 12
- 4.3. Replacing-reply-key Facility . . . . . . . . . . . . . . . 13
- 4.4. KDC-authentication Facility . . . . . . . . . . . . . . . 14
- 5. Requirements for Pre-Authentication Mechanisms . . . . . . . . 14
- 6. Tools for Use in Pre-Authentication Mechanisms . . . . . . . . 15
- 6.1. Combining Keys . . . . . . . . . . . . . . . . . . . . . . 15
- 6.2. Protecting Requests/Responses . . . . . . . . . . . . . . 16
- 6.3. Managing States for the KDC . . . . . . . . . . . . . . . 17
- 6.4. Pre-authentication Set . . . . . . . . . . . . . . . . . . 19
- 6.5. Definition of Kerberos FAST Padata . . . . . . . . . . . . 20
- 6.5.1. FAST and Encrypted Time Stamp . . . . . . . . . . . . 21
- 6.5.2. FAST Armors . . . . . . . . . . . . . . . . . . . . . 21
- 6.5.3. FAST Request . . . . . . . . . . . . . . . . . . . . . 22
- 6.5.4. FAST Response . . . . . . . . . . . . . . . . . . . . 26
- 6.5.5. Error Messages used with Kerberos FAST . . . . . . . . 28
- 6.6. Authentication Strength Indication . . . . . . . . . . . . 28
- 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29
- 8. Security Considerations . . . . . . . . . . . . . . . . . . . 29
- 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 30
- 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 30
- 10.1. Normative References . . . . . . . . . . . . . . . . . . . 30
- 10.2. Informative References . . . . . . . . . . . . . . . . . . 30
- Appendix A. ASN.1 module . . . . . . . . . . . . . . . . . . . . 30
- Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 33
- Intellectual Property and Copyright Statements . . . . . . . . . . 34
+ 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
+ 2. Conventions and Terminologies Used in This Document . . . . . 5
+ 3. Model for Pre-Authentication . . . . . . . . . . . . . . . . . 5
+ 3.1. Information Managed by the Pre-authentication Model . . . 6
+ 3.2. Initial Pre-authentication Required Error . . . . . . . . 8
+ 3.3. Client to KDC . . . . . . . . . . . . . . . . . . . . . . 9
+ 3.4. KDC to Client . . . . . . . . . . . . . . . . . . . . . . 10
+ 4. Pre-Authentication Facilities . . . . . . . . . . . . . . . . 10
+ 4.1. Client-authentication Facility . . . . . . . . . . . . . . 12
+ 4.2. Strengthening-reply-key Facility . . . . . . . . . . . . . 12
+ 4.3. Replacing-reply-key Facility . . . . . . . . . . . . . . . 13
+ 4.4. KDC-authentication Facility . . . . . . . . . . . . . . . 14
+ 5. Requirements for Pre-Authentication Mechanisms . . . . . . . . 14
+ 6. Tools for Use in Pre-Authentication Mechanisms . . . . . . . . 15
+ 6.1. Combining Keys . . . . . . . . . . . . . . . . . . . . . . 15
+ 6.2. Protecting Requests/Responses . . . . . . . . . . . . . . 16
+ 6.3. Managing States for the KDC . . . . . . . . . . . . . . . 17
+ 6.4. Pre-authentication Set . . . . . . . . . . . . . . . . . . 19
+ 6.5. Definition of Kerberos FAST Padata . . . . . . . . . . . . 20
+ 6.5.1. FAST and Encrypted Time Stamp . . . . . . . . . . . . 21
+ 6.5.2. FAST Armors . . . . . . . . . . . . . . . . . . . . . 21
+ 6.5.3. FAST Request . . . . . . . . . . . . . . . . . . . . . 22
+ 6.5.4. FAST Response . . . . . . . . . . . . . . . . . . . . 26
+ 6.5.5. Error Messages used with Kerberos FAST . . . . . . . . 28
+ 6.6. Authentication Strength Indication . . . . . . . . . . . . 28
+ 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29
+ 8. Security Considerations . . . . . . . . . . . . . . . . . . . 29
+ 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 30
+ 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 30
+ 10.1. Normative References . . . . . . . . . . . . . . . . . . . 30
+ 10.2. Informative References . . . . . . . . . . . . . . . . . . 30
+ Appendix A. ASN.1 module . . . . . . . . . . . . . . . . . . . . 30
+ Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 33
+ Intellectual Property and Copyright Statements . . . . . . . . . . 34
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-1. Introduction
+1. Introduction
- The core Kerberos specification [RFC4120] treats pre-authentication
+ The core Kerberos specification [RFC4120] treats pre-authentication
data as an opaque typed hole in the messages to the KDC that may
influence the reply key used to encrypt the KDC reply. This
generality has been useful: pre-authentication data is used for a
@@ -320,7 +192,7 @@ Table of Contents
authentication mechanisms perform as well as how these functions
affect the state of the request and reply. In addition several
common tools needed by pre-authentication mechanisms are provided.
- Unlike [RFC3961], this framework is not complete--it does not
+ Unlike [RFC3961], this framework is not complete--it does not
describe all the inputs and outputs for the pre-authentication
mechanisms. Pre-Authentication mechanism designers should try to be
consistent with this framework because doing so will make their
@@ -335,9 +207,9 @@ Table of Contents
protected channel. Based on FAST, pre-authentication mechanisms can
extend Kerberos with ease, to support, for example, password
authenticated key exchange (PAKE) protocols with zero knowledge
- password proof (ZKPP) [EKE] [IEEE1363.2]. Any pre-authentication
+ password proof (ZKPP) [EKE] [IEEE1363.2]. Any pre-authentication
mechanism can be encapsulated in the FAST messages as defined in
- Section 6.5. A pre-authentication type carried within FAST is called
+ Section 6.5. A pre-authentication type carried within FAST is called
a FAST factor. Creating a FAST factor is the easiest path to create
a new pre-authentication mechanism. FAST factors are significantly
easier to analyze from a security standpoint than other pre-
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authentication mechanisms outside of FAST.
This document should be read only after reading the documents
- describing the Kerberos cryptography framework [RFC3961] and the core
- Kerberos protocol [RFC4120]. This document freely uses terminology
+ describing the Kerberos cryptography framework [RFC3961] and the core
+ Kerberos protocol [RFC4120]. This document freely uses terminology
and notation from these documents without reference or further
explanation.
-2. Conventions and Terminologies Used in This Document
+2. Conventions and Terminologies Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
- document are to be interpreted as described in [RFC2119].
+ document are to be interpreted as described in [RFC2119].
The word padata is used as the shorthand of pre-authentication data.
@@ -377,7 +249,7 @@ Table of Contents
exchanged between the client and the KDC.
-3. Model for Pre-Authentication
+3. Model for Pre-Authentication
When a Kerberos client wishes to obtain a ticket using the
authentication server, it sends an initial Authentication Service
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These models for state management are in apparent conflict. For many
@@ -418,7 +290,7 @@ Table of Contents
needs to provide the client with a cookie to include in future
requests to capture the current state of the authentication session.
Handling of multiple round-trip mechanisms is discussed in
- Section 6.3.
+ Section 6.3.
This framework specifies the behavior of Kerberos pre-authentication
mechanisms used to identify users or to modify the reply key used to
@@ -434,7 +306,7 @@ Table of Contents
implementations process the padata at each step of the AS request
process.
-3.1. Information Managed by the Pre-authentication Model
+3.1. Information Managed by the Pre-authentication Model
The following information is maintained by the client and KDC as each
request is being processed:
@@ -454,14 +326,14 @@ Table of Contents
Conceptually, the reply key is initially the long-term key of the
principal. However, principals can have multiple long-term keys
because of support for multiple encryption types, salts and
- string2key parameters. As described in Section 5.2.7.5 of the
- Kerberos protocol [RFC4120], the KDC sends PA-ETYPE-INFO2 to notify
+ string2key parameters. As described in Section 5.2.7.5 of the
+ Kerberos protocol [RFC4120], the KDC sends PA-ETYPE-INFO2 to notify
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the client what types of keys are available. Thus in full
@@ -493,17 +365,17 @@ Table of Contents
because the primary purpose of pre-authentication is to authenticate
the client identity before issuing a ticket. The handling of
authentication strength using various authentication mechanisms is
- discussed in Section 6.6.
+ discussed in Section 6.6.
Initially the reply key has not been used. A pre-authentication
mechanism that uses the reply key to encrypt or checksum some data in
the generation of new keys MUST indicate that the reply key is used.
This state is maintained by the client and the KDC to enforce the
- security requirement stated in Section 4.3 that the reply key cannot
+ security requirement stated in Section 4.3 that the reply key cannot
be replaced after it is used.
Initially the reply key has not been replaced. If a mechanism
- implements the Replace Reply Key facility discussed in Section 4.3,
+ implements the Replace Reply Key facility discussed in Section 4.3,
then the state MUST be updated to indicate that the reply key has
been replaced. Once the reply key has been replaced, knowledge of
the reply key is insufficient to authenticate the client. The reply
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Without pre-authentication, the client knows that the KDC reply is
@@ -546,15 +418,15 @@ Table of Contents
known public key or providing a ticket for the client machine as a
service.
-3.2. Initial Pre-authentication Required Error
+3.2. Initial Pre-authentication Required Error
Typically a client starts a conversation by sending an initial
request with no pre-authentication. If the KDC requires pre-
authentication, then it returns a KDC_ERR_PREAUTH_REQUIRED message.
After the first reply with the KDC_ERR_PREAUTH_REQUIRED error code,
the KDC returns the error code KDC_ERR_MORE_PREAUTH_DATA_NEEDED
- (defined in Section 6.3) for pre-authentication configurations that
- use multi-round-trip mechanisms; see Section 3.4 for details of that
+ (defined in Section 6.3) for pre-authentication configurations that
+ use multi-round-trip mechanisms; see Section 3.4 for details of that
case. [[anchor3: Is it desirable to define a new error code for this?
Probably but we need to call out to the WG.]]
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mechanisms may only be useful in authentication sets; others may be
@@ -591,7 +463,7 @@ Table of Contents
the KDC needs to expose cipher text encrypted in a weak key before
the client has proven knowledge of that key.
-3.3. Client to KDC
+3.3. Client to KDC
This description assumes that a client has already received a
KDC_ERR_PREAUTH_REQUIRED from the KDC. If the client performs
@@ -606,7 +478,7 @@ Table of Contents
When processing the response to the KDC_ERR_PREAUTH_REQUIRED, the
client MAY ignore any padata it chooses unless doing so violates a
specification to which the client conforms. Clients conforming to
- this specification MUST NOT ignore the padata defined in Section 6.3.
+ this specification MUST NOT ignore the padata defined in Section 6.3.
Clients SHOULD process padata unrelated to this framework or other
means of authenticating the user. Clients SHOULD choose one
authentication set or mechanism that could lead to authenticating the
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order in which they will appear in the next request, updating the
state as appropriate. The request is sent when it is complete.
-3.4. KDC to Client
+3.4. KDC to Client
When a KDC receives an AS request from a client, it needs to
determine whether it will respond with an error or an AS reply.
@@ -645,7 +517,7 @@ Table of Contents
From the standpoint of evaluating the pre-authentication, the KDC
first starts by initializing the pre-authentication state. It then
- processes the padata in the request. As mentioned in Section 3.3,
+ processes the padata in the request. As mentioned in Section 3.3,
the KDC MAY ignore padata that is inappropriate for the configuration
and MUST ignore padata of an unknown type.
@@ -670,22 +542,22 @@ Table of Contents
input. After the padata is generated, the error response is sent.
Typically the errors with the code KDC_ERR_MORE_PREAUTH_DATA_NEEDED
in a converstation will include KDC state as discussed in
- Section 6.3.
+ Section 6.3.
To generate a final reply, the KDC generates the padata modifying the
pre-authentication state as necessary. Then it generates the final
response, encrypting it in the current pre-authentication reply key.
-4. Pre-Authentication Facilities
+4. Pre-Authentication Facilities
Pre-Authentication mechanisms can be thought of as providing various
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conceptual facilities. This serves two useful purposes. First,
@@ -711,8 +583,8 @@ Table of Contents
provided by a single mechanism without complicating the security
analysis.
- According to Kerberos extensibility rules (Section 1.5 of the
- Kerberos specification [RFC4120]), an extension MUST NOT change the
+ According to Kerberos extensibility rules (Section 1.5 of the
+ Kerberos specification [RFC4120]), an extension MUST NOT change the
semantics of a message unless a recipient is known to understand that
extension. Because a client does not know that the KDC supports a
particular pre-authentication mechanism when it sends an initial
@@ -731,29 +603,29 @@ Table of Contents
parts. The first part proposes a change to the core semantic--for
example proposes a new reply key. The second part acknowledges that
the extension is understood and that the change takes effect.
- Section 4.2 discusses how to design mechanisms that modify the reply
+ Section 4.2 discusses how to design mechanisms that modify the reply
key to be split into a proposal and acceptance without requiring
additional round trips to use the new reply key in subsequent pre-
- authentication. Other changes in the state described in Section 3.1
+ authentication. Other changes in the state described in Section 3.1
can safely be ignored by a KDC that does not understand a mechanism.
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Mechanisms that modify the behavior of the request outside the scope
of this framework need to carefully consider the Kerberos
extensibility rules to avoid similar problems.
-4.1. Client-authentication Facility
+4.1. Client-authentication Facility
The client authentication facility proves the identity of a user to
the KDC before a ticket is issued. Examples of mechanisms
implementing this facility include the encrypted timestamp facility
- defined in Section 5.2.7.2 of the Kerberos specification [RFC4120].
+ defined in Section 5.2.7.2 of the Kerberos specification [RFC4120].
Mechanisms that provide this facility are expected to mark the client
as authenticated.
@@ -762,22 +634,22 @@ Table of Contents
reply. Otherwise, an attacker can intercept the pre-authentication
exchange and get a reply to attack. One way of proving the client
knows the reply key is to implement the Replace Reply Key facility
- along with this facility. The PKINIT mechanism [RFC4556] implements
+ along with this facility. The PKINIT mechanism [RFC4556] implements
Client Authentication alongside Replace Reply Key.
If the reply key has been replaced, then mechanisms such as
encrypted-timestamp that rely on knowledge of the reply key to
authenticate the client MUST NOT be used.
-4.2. Strengthening-reply-key Facility
+4.2. Strengthening-reply-key Facility
Particularly, when dealing with keys based on passwords, it is
desirable to increase the strength of the key by adding additional
secrets to it. Examples of sources of additional secrets include the
results of a Diffie-Hellman key exchange or key bits from the output
- of a smart card [KRB-WG.SAM]. Typically these additional secrets can
+ of a smart card [KRB-WG.SAM]. Typically these additional secrets can
be first combined with the existing reply key and then converted to a
- protocol key using tools defined in Section 6.1.
+ protocol key using tools defined in Section 6.1.
If a mechanism implementing this facility wishes to modify the reply
key before knowing that the other party in the exchange supports the
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with the outer level, one authentication set or mechanism is
@@ -833,7 +705,7 @@ Table of Contents
because we also recommend client authentication facilities be tied to
the reply key.
-4.3. Replacing-reply-key Facility
+4.3. Replacing-reply-key Facility
The Replace Reply Key facility replaces the key in which a successful
AS reply will be encrypted. This facility can only be used in cases
@@ -851,9 +723,9 @@ Table of Contents
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rules require that the reply key not be changed unless both sides of
@@ -861,9 +733,9 @@ Table of Contents
it will likely be more common for both sides to know that the
facility is available by the time that the new key is available to be
used. However, mechanism designers can use a container for padata in
- a proposal message as discussed in Section 4.2 if appropriate.
+ a proposal message as discussed in Section 4.2 if appropriate.
-4.4. KDC-authentication Facility
+4.4. KDC-authentication Facility
This facility verifies that the reply comes from the expected KDC.
In traditional Kerberos, the KDC and the client share a key, so if
@@ -878,7 +750,7 @@ Table of Contents
having been verified.
-5. Requirements for Pre-Authentication Mechanisms
+5. Requirements for Pre-Authentication Mechanisms
This section lists requirements for specifications of pre-
authentication mechanisms.
@@ -897,7 +769,7 @@ Table of Contents
addition, such mechanisms should also define a pa-hint to be included
in authentication sets. Often, the same information included in the
padata-value is appropriate to include in the pa-hint (as defined in
- Section 6.4).
+ Section 6.4).
In order to ease security analysis the mechanism specification should
describe what facilities from this document are offered by the
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applicable to any FAST factor that provides authentication
@@ -924,7 +796,7 @@ Table of Contents
to be able to cause the protocol negotiation to fail by modifying
plaintext. More significant attacks should be evaluated carefully.
- As discussed in Section 6.3, there is no guarantee that a client will
+ As discussed in Section 6.3, there is no guarantee that a client will
use the same KDCs for all messages in a conversation. The mechanism
specification needs to show why the mechanism is secure in this
situation. The hardest problem to deal with, especially for
@@ -933,14 +805,14 @@ Table of Contents
to any KDC.
-6. Tools for Use in Pre-Authentication Mechanisms
+6. Tools for Use in Pre-Authentication Mechanisms
This section describes common tools needed by multiple pre-
authentication mechanisms. By using these tools mechanism designers
can use a modular approach to specify mechanism details and ease
security analysis.
-6.1. Combining Keys
+6.1. Combining Keys
Frequently a weak key need to be combined with a stronger key before
use. For example, passwords are typically limited in size and
@@ -952,20 +824,20 @@ Table of Contents
KRB-FX-CF1() is defined to combine two pass-phrases.
- KRB-FX-CF1(UTF-8 string, UTF-8 string) -> (UTF-8 string)
- KRB-FX-CF1(x, y) -> x || y
+ KRB-FX-CF1(UTF-8 string, UTF-8 string) -> (UTF-8 string)
+ KRB-FX-CF1(x, y) -> x || y
Where || denotes concatenation. The strength of the final key is
roughly the total strength of the individual keys being combined
- assuming that the string_to_key() function [RFC3961] uses all its
+ assuming that the string_to_key() function [RFC3961] uses all its
input evenly.
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An example usage of KRB-FX-CF1() is when a device provides random but
@@ -974,33 +846,33 @@ Table of Contents
combined using KRB-FX-CF1().
KRB-FX-CF2() combines two protocol keys based on the pseudo-random()
- function defined in [RFC3961].
+ function defined in [RFC3961].
Given two input keys, K1 and K2, where K1 and K2 can be of two
different enctypes, the output key of KRB-FX-CF2(), K3, is derived as
follows:
KRB-FX-CF2(protocol key, protocol key, octet string,
- octet string) -> (protocol key)
+ octet string) -> (protocol key)
- PRF+(K1, pepper1) -> octet-string-1
- PRF+(K2, pepper2) -> octet-string-2
- KRB-FX-CF2(K1, K2, pepper1, pepper2) ->
+ PRF+(K1, pepper1) -> octet-string-1
+ PRF+(K2, pepper2) -> octet-string-2
+ KRB-FX-CF2(K1, K2, pepper1, pepper2) ->
random-to-key(octet-string-1 ^ octet-string-2)
Where ^ denotes the exclusive-OR operation. PRF+() is defined as
follows:
- PRF+(protocol key, octet string) -> (octet string)
+ PRF+(protocol key, octet string) -> (octet string)
- PRF+(key, shared-info) -> pseudo-random( key, 1 || shared-info ) ||
+ PRF+(key, shared-info) -> pseudo-random( key, 1 || shared-info ) ||
pseudo-random( key, 2 || shared-info ) ||
pseudo-random( key, 3 || shared-info ) || ...
Here the counter value 1, 2, 3 and so on are encoded as a one-octet
integer. The pseudo-random() operation is specified by the enctype
of the protocol key. PRF+() uses the counter to generate enough bits
- as needed by the random-to-key() [RFC3961] function for the
+ as needed by the random-to-key() [RFC3961] function for the
encryption type specified for the resulting key; unneeded bits are
removed from the tail.
@@ -1009,19 +881,19 @@ Table of Contents
that if the two keys being combined are the same, the resulting key
is not a trivial key.
-6.2. Protecting Requests/Responses
+6.2. Protecting Requests/Responses
Mechanism designers SHOULD protect clear text portions of pre-
authentication data. Various denial of service attacks and downgrade
attacks against Kerberos are possible unless plaintexts are somehow
protected against modification. An early design goal of Kerberos
- Version 5 [RFC4120] was to avoid encrypting more of the
+ Version 5 [RFC4120] was to avoid encrypting more of the
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+
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authentication exchange that was required. (Version 4 doubly-
@@ -1039,9 +911,9 @@ Table of Contents
provide a checksum of all the messages exchanged on the wire in the
conversation, and the checksum is then verified by the receiver.
- Primitives defined in [RFC3961] are RECOMMENDED for integrity
+ Primitives defined in [RFC3961] are RECOMMENDED for integrity
protection and confidentiality. Mechanisms based on these primitives
- have the benefit of crypto-agility provided by [RFC3961].
+ have the benefit of crypto-agility provided by [RFC3961].
The advantage afforded by crypto-agility is the ability to avoid a
multi-year standardization and deployment cycle to fix a problem that
@@ -1050,13 +922,13 @@ Table of Contents
New mechanisms MUST NOT be hard-wired to use a specific algorithm.
- Note that data used by FAST factors (defined in Section 6.5) are
+ Note that data used by FAST factors (defined in Section 6.5) are
encrypted in a protected channel, in most cases, therefore no un-
authenticated-text issue is associated with these mechanisms.
However mechanism designers MUST consider the case carefully when the
KDC authentication is not provided by Kerberos FAST.
-6.3. Managing States for the KDC
+6.3. Managing States for the KDC
[[anchor11: Kerberos is stateless today. We can either maintain that
and store all the state in a cookie or change that and require
@@ -1075,9 +947,9 @@ Table of Contents
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+Zhu & Hartman Expires September 6, 2007 [Page 17]
+
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KDC_ERR_PREAUTH_EXPIRED TBA
@@ -1100,12 +972,12 @@ Table of Contents
PA_FX_COOKIE TBA
-- Stateless cookie that is not tied to a specific KDC.
- The corresponding padata-value field [RFC4120] contains the
- Distinguished Encoding Rules (DER) [X60] [X690] encoding of the
+ The corresponding padata-value field [RFC4120] contains the
+ Distinguished Encoding Rules (DER) [X60] [X690] encoding of the
following Abstract Syntax Notation One (ASN.1) type PA-FX-COOKIE:
PA-FX-COOKIE ::= SEQUENCE {
- Cookie [1] OCTET STRING,
+ Cookie [1] OCTET STRING,
-- Opaque data, for use to associate all the messages in a
-- single conversation between the client and the KDC.
-- This can be generated by either the client or the KDC.
@@ -1123,7 +995,7 @@ Table of Contents
design. The content of the Cookie field is likely specific to the
pre-authentication mechanisms used to authenticate the client. In
order to compute the finished field in the KrbFastRespons structure
- as defined in Section 6.5.4, all the previous messages in the
+ as defined in Section 6.5.4, all the previous messages in the
conversation MUST be included in the Cookie. If a client
authentication response can be replayed to multiple KDCs via the
PA_FX_COOKIE mechanism, an expiration in the Cookie is RECOMMENDED to
@@ -1131,9 +1003,9 @@ Table of Contents
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+
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If at least one more message for a mechanism or a mechanism set is
@@ -1143,7 +1015,7 @@ Table of Contents
KDC_ERR_MORE_PREAUTH_DATA_NEEDED TBA
-6.4. Pre-authentication Set
+6.4. Pre-authentication Set
If all mechanisms in a group need to successfully complete in order
to authenticate a client, the client and the KDC SHOULD use the
@@ -1155,15 +1027,15 @@ Table of Contents
PA-AUTHENTICATION-SET ::= SEQUENCE OF PA-AUTHENTICATION-SET-ELEM
PA-AUTHENTICATION-SET-ELEM ::= SEQUENCE {
- pa-type [1] Int32,
+ pa-type [1] Int32,
-- same as padata-type.
- pa-hint [2] OCTET STRING,
+ pa-hint [2] OCTET STRING,
-- hint data.
...
}
The pa-type field of the PA-AUTHENTICATION-SET-ELEM structure
- contains the corresponding value of padata-type in PA-DATA [RFC4120].
+ contains the corresponding value of padata-type in PA-DATA [RFC4120].
Associated with the pa-type is a pa-hint, which is an octet-string
specified by the pre-authentication mechanism. This hint may provide
information for the client which helps it determine whether the
@@ -1187,9 +1059,9 @@ Table of Contents
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+
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When indicating which sets of padata are supported, the KDC includes
@@ -1199,7 +1071,7 @@ Table of Contents
the authentication set, when the first mechanism completes, the
client and the KDC will proceed with the second mechanism, and so on
until all mechanisms complete successfully. The PA_FX_COOKIE as
- defined in Section 6.3 MUST be sent by the KDC along with the first
+ defined in Section 6.3 MUST be sent by the KDC along with the first
message that contains a PA-AUTHENTICATION-SET, in order to keep track
of KDC states.
@@ -1210,7 +1082,7 @@ Table of Contents
we can simplify the UI for login. I propose that we make this
requirement. WG agreement required.]]
-6.5. Definition of Kerberos FAST Padata
+6.5. Definition of Kerberos FAST Padata
The cipher text exposure when using the encrypted timestamp pre-
authentication data is a security concern for Kerberos. Attackers
@@ -1234,26 +1106,26 @@ Table of Contents
instead of full-blown pre-authentication mechanisms.
FAST factors that are pre-authentication mechanisms MUST meet the
- requirements in Section 5.
+ requirements in Section 5.
FAST employs an armoring scheme. The armor can be a host Ticket
Granting Ticket (TGT), or an anonymous TGT obtained based on
- anonymous PKINIT [KRB-ANON], or a pre-shared long term key such as a
+ anonymous PKINIT [KRB-ANON], or a pre-shared long term key such as a
host key. The armoring TGT can be a cross-realm TGT. The rest of
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+
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this section describes the types of armors and the messages used by
FAST.
-6.5.1. FAST and Encrypted Time Stamp
+6.5.1. FAST and Encrypted Time Stamp
- FAST provides new behavior for encrypted time stamp [RFC4120]. When
+ FAST provides new behavior for encrypted time stamp [RFC4120]. When
used as a FAST factor, this mechanism provides stronger security
guarantees.
@@ -1262,13 +1134,13 @@ Table of Contents
authenticate the client, as a FAST factor to avoid security exposure.
The encrypted timestamp FAST factor MUST fill out the encrypted rep-
- key-package field as described in Section 6.5.4. It provides the
+ key-package field as described in Section 6.5.4. It provides the
following facilities: client-authentication, replacing-reply-key,
KDC-authentication. It does not provide the strengthening-reply-key
facility. The security considerations section of this document
provides an explanation why the security requirements are met.
-6.5.2. FAST Armors
+6.5.2. FAST Armors
An armor key is used to encrypt pre-authentication data in the FAST
request and the response. The ArmorData structure is used to
@@ -1277,9 +1149,9 @@ Table of Contents
an OCTET STRING contains the data.
KrbFastArmor ::= SEQUENCE {
- armor-type [1] Int32,
+ armor-type [1] Int32,
-- Type of the armor.
- armor-value [2] OCTET STRING,
+ armor-value [2] OCTET STRING,
-- Value of the armor.
...
}
@@ -1299,12 +1171,12 @@ Table of Contents
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+Zhu & Hartman Expires September 6, 2007 [Page 21]
+
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-6.5.2.1. Ticket-based Armors
+6.5.2.1. Ticket-based Armors
The FX_FAST_ARMOR_AP_REQUEST armor type is based on a Kerberos TGT.
The armor-value field of an FX_FAST_ARMOR_AP_REQUEST armor contains
@@ -1321,7 +1193,7 @@ Table of Contents
the armor ticket.
2. Otherwise, the client's host machine cannot obtain a host ticket
- strictly based on RFC4120, but the KDC has a signing asymmetric
+ strictly based on RFC4120, but the KDC has a signing asymmetric
key that the client can verify its binding with the expected KDC,
the client then can use anonymous PKINIT to obtain a anonymous
TGT, and use that TGT to as the armor ticket.
@@ -1335,7 +1207,7 @@ Table of Contents
ticket it has, the KDC and client MUST initialize the pre-
authentication state to an unverified KDC.
-6.5.2.2. Key-based Armors
+6.5.2.2. Key-based Armors
The FX_FAST_ARMOR_KEY_ID armor type is used to carry an identifier of
a key that is shared between the client host and the KDC. The
@@ -1348,41 +1220,41 @@ Table of Contents
host key. [[anchor19: Do we believe this has sufficient value to
specify or do we want to assume all armor comes from tickets?]]
-6.5.3. FAST Request
+6.5.3. FAST Request
A padata type PA_FX_FAST is defined for the Kerberos FAST pre-
authentication padata. The corresponding padata-value field
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+Zhu & Hartman Expires September 6, 2007 [Page 22]
+
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- [RFC4120] contains the DER encoding of the ASN.1 type PA-FX-FAST-
+ [RFC4120] contains the DER encoding of the ASN.1 type PA-FX-FAST-
REQUEST.
PA_FX_FAST TBA
-- Padata type for Kerberos FAST
PA-FX-FAST-REQUEST ::= CHOICE {
- armored-data [1] KrbFastAmoredReq,
+ armored-data [1] KrbFastAmoredReq,
...
}
KrbFastAmoredReq ::= SEQUENCE {
- armor [1] KrbFastArmor OPTIONAL,
+ armor [1] KrbFastArmor OPTIONAL,
-- Contains the armor that determines the armor key.
-- MUST be present in AS-REQ.
-- MUST be absent in TGS-REQ.
- req-checksum [2] Checksum,
+ req-checksum [2] Checksum,
-- Checksum performed over the type KDC-REQ-BODY.
-- The checksum key is the armor key, the checksum
-- type is the required checksum type for the enctype of
-- the armor key, and the key usage number is
-- KEY_USAGE_FAST_REA_CHKSUM.
- enc-fast-req [3] EncryptedData, -- KrbFastReq --
+ enc-fast-req [3] EncryptedData, -- KrbFastReq --
-- The encryption key is the armor key, and the key usage
-- number is KEY_USAGE_FAST_ENC.
...
@@ -1411,9 +1283,9 @@ Table of Contents
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+
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o When a KrbFastAmoredReq is included in a TGS request, the armor
@@ -1430,15 +1302,15 @@ Table of Contents
The KrbFastReq structure contains the following information:
KrbFastReq ::= SEQUENCE {
- fast-options [0] FastOptions,
+ fast-options [0] FastOptions,
-- Additional options.
- padata [1] SEQUENCE OF PA-DATA,
+ padata [1] SEQUENCE OF PA-DATA,
-- padata typed holes.
- crealm [2] Realm OPTIONAL,
- cname [3] PrincipalName OPTIONAL,
+ crealm [2] Realm OPTIONAL,
+ cname [3] PrincipalName OPTIONAL,
-- Contains the client realm and the client name.
-- If present, the client name and realm in the
- -- AS_REQ KDC-REQ-BODY [RFC4120] MUST be ignored.
+ -- AS_REQ KDC-REQ-BODY [RFC4120] MUST be ignored.
...
}
@@ -1467,16 +1339,16 @@ Table of Contents
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+
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unknown non-critical options.
The anonymous Option
- The Kerberos response defined in [RFC4120] contains the client
+ The Kerberos response defined in [RFC4120] contains the client
identity in clear text, This makes traffic analysis
straightforward. The anonymous option is designed to complicate
traffic analysis performed over the messages exchanged between the
@@ -1488,10 +1360,10 @@ Table of Contents
The kdc-referrals Option
- The Kerberos client described in [RFC4120] has to request referral
+ The Kerberos client described in [RFC4120] has to request referral
TGTs along the authentication path in order to get a service
ticket for the target service. The Kerberos client described in
- the [REFERRALS] need to contact the AS specified in the error
+ the [REFERRALS] need to contact the AS specified in the error
response in order to complete client referrals. The kdc-referrals
option is designed to minimize the number of messages that need to
be processed by the client. This option is useful when, for
@@ -1499,7 +1371,7 @@ Table of Contents
has high latency, or the client has limited computational
capabilities. If the kdc-referrals option is set, the KDC that
honors this option acts as the client to follow AS referrals and
- TGS referrals [REFERRALS], and return the ticket thus-obtained
+ TGS referrals [REFERRALS], and return the ticket thus-obtained
using the reply key expected by the client. The kdc-referrals
option can be implemented when the KDC knows the reply key. The
KDC can ignore kdc-referrals option when it does not understand it
@@ -1508,7 +1380,7 @@ Table of Contents
is not honored by the KDC, unless otherwise specified.
The padata field contains a list of PA-DATA structures as described
- in Section 5.2.7 of [RFC4120]. These PA-DATA structures can contain
+ in Section 5.2.7 of [RFC4120]. These PA-DATA structures can contain
FAST factors. They can also be used as generic typed-holes to
contain data not intended for proving the client's identity or
establishing a reply key, but for protocol extensibility.
@@ -1516,33 +1388,33 @@ Table of Contents
The crealm field and the cname field identify the client principal in
the ticket request. If either the crealm field or the cname field is
present, the corresponding crealm or cname field in the KDC-REQ-BODY
- [RFC4120] of an AS-REQ MUST be ignored. The client can fill in these
+ [RFC4120] of an AS-REQ MUST be ignored. The client can fill in these
fields in the KrbFastReq structure and leaves the cname field and the
crealm field KDC-REQ-BODY absent, thus conceals its identity in the
AS-REQ.
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+
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-6.5.4. FAST Response
+6.5.4. FAST Response
The KDC that supports the PA_FX_FAST padata MUST include a PA_FX_FAST
padata element in the KDC reply and/or the error response, when the
client and the KDC agreed upon the armor key. The corresponding
- padata-value field [RFC4120] in the KDC response is the DER encoding
+ padata-value field [RFC4120] in the KDC response is the DER encoding
of the ASN.1 type PA-FX-FAST-REPLY.
PA-FX-FAST-REPLY ::= CHOICE {
- armored-data [1] KrbFastArmoredRep,
+ armored-data [1] KrbFastArmoredRep,
...
}
KrbFastArmoredRep ::= SEQUENCE {
- enc-fast-rep [1] EncryptedData, -- KrbFastResponse --
+ enc-fast-rep [1] EncryptedData, -- KrbFastResponse --
-- The encryption key is the armor key in the request, and
-- the key usage number is KEY_USAGE_FAST_REP.
...
@@ -1568,9 +1440,9 @@ Table of Contents
The KrbFastResponse structure contains the following information:
KrbFastResponse ::= SEQUENCE {
- padata [1] SEQUENCE OF PA-DATA,
+ padata [1] SEQUENCE OF PA-DATA,
-- padata typed holes.
- finished [2] KrbFastFinished OPTIONAL,
+ finished [2] KrbFastFinished OPTIONAL,
-- MUST be present if the client is authenticated,
-- absent otherwise.
-- Typically this is present if and only if the containing
@@ -1579,15 +1451,15 @@ Table of Contents
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+
+Internet-Draft Kerberos Preauth Framework March 2007
}
The padata field in the KrbFastResponse structure contains a list of
- PA-DATA structures as described in Section 5.2.7 of [RFC4120]. These
+ PA-DATA structures as described in Section 5.2.7 of [RFC4120]. These
PA-DATA structures are used to carry data advancing the exchange
specific for the FAST factors. They can also be used as generic
typed-holes for protocol extensibility.
@@ -1600,20 +1472,20 @@ Table of Contents
The KrbFastFinished structure contains the following information:
KrbFastFinished ::= SEQUENCE {
- timestamp [1] KerberosTime,
- usec [2] Microseconds,
+ timestamp [1] KerberosTime,
+ usec [2] Microseconds,
-- timestamp and usec represent the time on the KDC when
-- the reply was generated.
- rep-key-package [3] EncryptedData OPTIONAL,
+ rep-key-package [3] EncryptedData OPTIONAL,
-- EncryptionKey --
-- This, if present, replaces the reply key for AS and TGS.
-- The encryption key is the client key, unless otherwise
-- specified. The key usage number is
-- KEY_USAGE_FAST_FINISHED.
- crealm [4] Realm,
- cname [5] PrincipalName,
+ crealm [4] Realm,
+ cname [5] PrincipalName,
-- Contains the client realm and the client name.
- checksum [6] Checksum,
+ checksum [6] Checksum,
-- Checksum performed over all the messages in the
-- conversation, except the containing message.
-- The checksum key is the ticket session key of the reply
@@ -1626,8 +1498,8 @@ Table of Contents
The timestamp and usec fields represent the time on the KDC when the
reply ticket was generated, these fields have the same semantics as
- the corresponding-identically-named fields in Section 5.6.1 of
- [RFC4120]. The client MUST use the KDC's time in these fields
+ the corresponding-identically-named fields in Section 5.6.1 of
+ [RFC4120]. The client MUST use the KDC's time in these fields
thereafter when using the returned ticket. Note that the KDC's time
in AS-REP may not match the authtime in the reply ticket if the kdc-
referrals option is requested and honored by the KDC.
@@ -1635,9 +1507,9 @@ Table of Contents
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The rep-key-package field, if present, contains the reply key
@@ -1657,17 +1529,17 @@ Table of Contents
enctype of that key, and the key usage number is
KEY_USAGE_FAST_FINISHED.
-6.5.5. Error Messages used with Kerberos FAST
+6.5.5. Error Messages used with Kerberos FAST
If the Kerberos FAST padata was included in the request, unless
otherwise specified, the e-data field of the KRB-ERROR message
- [RFC4120] contains the ASN.1 DER encoding of the type METHOD-DATA
- [RFC4120], where a PA_FX_FAST padata element is included and it
+ [RFC4120] contains the ASN.1 DER encoding of the type METHOD-DATA
+ [RFC4120], where a PA_FX_FAST padata element is included and it
contains the DER encoding of the type PA-FX-FAST-REPLY. If the
e-data field of the KRB-ERROR message contains the DER encoding of a
TYPED-DATA, a typed data element TD_FX_FAST SHOULD be included in the
e-data if the Kerberos FAST padata is included in the request, and
- the corresponding data-value field [RFC4120] contains the ASN.1 DER
+ the corresponding data-value field [RFC4120] contains the ASN.1 DER
encoding of the type PA-FX-FAST-REPLY. In other words, the typed
data element type TD_FX_FAST is allocated to encapsulate the FAST
reply message in the error responses. If a PA-FX-FAST-REPLY is not
@@ -1683,7 +1555,7 @@ Table of Contents
TD_FX_FAST TBA
-- Typed data element type for Kerberos FAST
-6.6. Authentication Strength Indication
+6.6. Authentication Strength Indication
Implementations that have pre-authentication mechanisms offering
significantly different strengths of client authentication MAY choose
@@ -1691,9 +1563,9 @@ Table of Contents
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+Zhu & Hartman Expires September 6, 2007 [Page 28]
+
+Internet-Draft Kerberos Preauth Framework March 2007
into policy decisions. For example, some principals might require
@@ -1706,7 +1578,7 @@ Table of Contents
AD-authentication-strength TBA
The corresponding ad-data field contains the DER encoding of the pre-
- authentication data set as defined in Section 6.4. This set contains
+ authentication data set as defined in Section 6.4. This set contains
all the pre-authentication mechanisms that were used to authenticate
the client. If only one pre-authentication mechanism was used to
authenticate the client, the pre-authentication set contains one
@@ -1716,7 +1588,7 @@ Table of Contents
RELEVANT, thus it can be ignored if it is unknown to the receiver.
-7. IANA Considerations
+7. IANA Considerations
This document defines FAST factors, these are mini- and light-
weighted- pre-authentication mechanisms. A new IANA registry should
@@ -1724,7 +1596,7 @@ Table of Contents
"Specification Required".
-8. Security Considerations
+8. Security Considerations
The kdc-referrals option in the Kerberos FAST padata requests the KDC
to act as the client to follow referrals. This can overload the KDC.
@@ -1747,75 +1619,75 @@ Table of Contents
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+Zhu & Hartman Expires September 6, 2007 [Page 29]
+
+Internet-Draft Kerberos Preauth Framework March 2007
-9. Acknowledgements
+9. Acknowledgements
Several suggestions from Jeffery Hutzman based on early revisions of
this documents led to significant improvements of this document.
-10. References
+10. References
-10.1. Normative References
+10.1. Normative References
- [KRB-ANON] Zhu, L., Leach, P. and Jaganathan, K., "Kerberos Anonymity
- Support", draft-ietf-krb-wg-anon, work in progress.
+ [KRB-ANON] Zhu, L., Leach, P. and Jaganathan, K., "Kerberos Anonymity
+ Support", draft-ietf-krb-wg-anon, work in progress.
- [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
- Requirement Levels", BCP 14, RFC 2119, March 1997.
+ [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
+ Requirement Levels", BCP 14, RFC 2119, March 1997.
- [RFC3961] Raeburn, K., "Encryption and Checksum Specifications for
- Kerberos 5", RFC 3961, February 2005.
+ [RFC3961] Raeburn, K., "Encryption and Checksum Specifications for
+ Kerberos 5", RFC 3961, February 2005.
- [RFC4120] Neuman, C., Yu, T., Hartman, S., and K. Raeburn, "The
- Kerberos Network Authentication Service (V5)", RFC 4120,
+ [RFC4120] Neuman, C., Yu, T., Hartman, S., and K. Raeburn, "The
+ Kerberos Network Authentication Service (V5)", RFC 4120,
July 2005.
- [REFERALS] Raeburn, K. et al, "Generating KDC Referrals to Locate
- Kerberos Realms", draft-ietf-krb-wg-kerberos-referrals,
+ [REFERALS] Raeburn, K. et al, "Generating KDC Referrals to Locate
+ Kerberos Realms", draft-ietf-krb-wg-kerberos-referrals,
work in progress.
- [SHA2] National Institute of Standards and Technology, "Secure
- Hash Standard (SHS)", Federal Information Processing
- Standards Publication 180-2, August 2002.
+ [SHA2] National Institute of Standards and Technology, "Secure
+ Hash Standard (SHS)", Federal Information Processing
+ Standards Publication 180-2, August 2002.
- [X680] ITU-T Recommendation X.680 (2002) | ISO/IEC 8824-1:2002,
+ [X680] ITU-T Recommendation X.680 (2002) | ISO/IEC 8824-1:2002,
Information technology - Abstract Syntax Notation One
(ASN.1): Specification of basic notation.
-
- [X690] ITU-T Recommendation X.690 (2002) | ISO/IEC 8825-1:2002,
+
+ [X690] ITU-T Recommendation X.690 (2002) | ISO/IEC 8825-1:2002,
Information technology - ASN.1 encoding Rules:
Specification of Basic Encoding Rules (BER), Canonical
Encoding Rules (CER) and Distinguished Encoding Rules
(DER).
-10.2. Informative References
+10.2. Informative References
- [EKE] Bellovin, S. M. and M. Merritt. "Augmented
- Encrypted Key Exchange: A Password-Based Protocol Secure
- Against Dictionary Attacks and Password File Compromise".
- Proceedings of the 1st ACM Conference on Computer and
+ [EKE] Bellovin, S. M. and M. Merritt. "Augmented
+ Encrypted Key Exchange: A Password-Based Protocol Secure
+ Against Dictionary Attacks and Password File Compromise".
+ Proceedings of the 1st ACM Conference on Computer and
Communications Security, ACM Press, November 1993.
-
- [HKDF] Dang, Q. and P. Polk, draft-dang-nistkdf, work in
+
+ [HKDF] Dang, Q. and P. Polk, draft-dang-nistkdf, work in
progress.
- [IEEE1363.2]
- IEEE P1363.2: Password-Based Public-Key Cryptography,
+ [IEEE1363.2]
+ IEEE P1363.2: Password-Based Public-Key Cryptography,
2004.
- [KRB-WG.SAM]
+ [KRB-WG.SAM]
Hornstein, K., Renard, K., Neuman, C., and G. Zorn,
"Integrating Single-use Authentication Mechanisms with
- Kerberos", draft-ietf-krb-wg-kerberos-sam-02.txt (work in
+ Kerberos", draft-ietf-krb-wg-kerberos-sam-02.txt (work in
progress), October 2003.
- [RFC4556] Zhu, L. and B. Tung, "Public Key Cryptography for Initial
- Authentication in Kerberos (PKINIT)", RFC 4556, June 2006.
+ [RFC4556] Zhu, L. and B. Tung, "Public Key Cryptography for Initial
+ Authentication in Kerberos (PKINIT)", RFC 4556, June 2006.
Appendix A. ASN.1 module
@@ -1831,18 +1703,18 @@ Appendix A. ASN.1 module
FROM KerberosV5Spec2 { iso(1) identified-organization(3)
dod(6) internet(1) security(5) kerberosV5(2)
modules(4) krb5spec2(2) };
- -- as defined in RFC 4120.
+ -- as defined in RFC 4120.
PA-FX-COOKIE ::= SEQUENCE {
-Zhu & Hartman Expires September 6, 2007 [Page 30]
-
-Internet-Draft Kerberos Preauth Framework March 2007
+Zhu & Hartman Expires September 6, 2007 [Page 30]
+
+Internet-Draft Kerberos Preauth Framework March 2007
- Cookie [1] OCTET STRING,
+ Cookie [1] OCTET STRING,
-- Opaque data, for use to associate all the messages in a
-- single conversation between the client and the KDC.
-- This can be generated by either the client or the KDC.
@@ -1855,61 +1727,61 @@ Appendix A. ASN.1 module
PA-AUTHENTICATION-SET ::= SEQUENCE OF PA-AUTHENTICATION-SET-ELEM
PA-AUTHENTICATION-SET-ELEM ::= SEQUENCE {
- pa-type [1] Int32,
+ pa-type [1] Int32,
-- same as padata-type.
- pa-hint [2] OCTET STRING,
+ pa-hint [2] OCTET STRING,
-- hint data.
...
}
PA-FX-FAST-REQUEST ::= CHOICE {
- armored-data [1] KrbFastAmoredReq,
+ armored-data [1] KrbFastAmoredReq,
...
}
KrbFastAmoredReq ::= SEQUENCE {
- armor [1] KrbFastArmor OPTIONAL,
+ armor [1] KrbFastArmor OPTIONAL,
-- Contains the armor that determines the armor key.
-- MUST be present in AS-REQ.
-- MUST be absent in TGS-REQ.
- req-checksum [2] Checksum,
+ req-checksum [2] Checksum,
-- Checksum performed over the type KDC-REQ-BODY.
-- The checksum key is the armor key, the checksum
-- type is the required checksum type for the enctype of
-- the armor key, and the key usage number is
-- KEY_USAGE_FAST_REA_CHKSUM.
- enc-fast-req [3] EncryptedData, -- KrbFastReq --
+ enc-fast-req [3] EncryptedData, -- KrbFastReq --
-- The encryption key is the armor key, and the key usage
-- number is KEY_USAGE_FAST_ENC.
...
}
KrbFastArmor ::= SEQUENCE {
- armor-type [1] Int32,
+ armor-type [1] Int32,
-- Type of the armor.
- armor-value [2] OCTET STRING,
+ armor-value [2] OCTET STRING,
-- Value of the armor.
...
-Zhu & Hartman Expires September 6, 2007 [Page 31]
-
-Internet-Draft Kerberos Preauth Framework March 2007
+Zhu & Hartman Expires September 6, 2007 [Page 31]
+
+Internet-Draft Kerberos Preauth Framework March 2007
}
KrbFastReq ::= SEQUENCE {
- fast-options [0] FastOptions,
+ fast-options [0] FastOptions,
-- Additional options.
- padata [1] SEQUENCE OF PA-DATA,
+ padata [1] SEQUENCE OF PA-DATA,
-- padata typed holes.
- crealm [2] Realm OPTIONAL,
- cname [3] PrincipalName OPTIONAL,
+ crealm [2] Realm OPTIONAL,
+ cname [3] PrincipalName OPTIONAL,
-- Contains the client realm and the client name.
-- If present, the client name and realm in the
- -- AS_REQ KDC-REQ-BODY [RFC4120] MUST be ignored.
+ -- AS_REQ KDC-REQ-BODY [RFC4120] MUST be ignored.
...
}
@@ -1919,21 +1791,21 @@ Appendix A. ASN.1 module
-- kdc-referrals(16)
PA-FX-FAST-REPLY ::= CHOICE {
- armored-data [1] KrbFastArmoredRep,
+ armored-data [1] KrbFastArmoredRep,
...
}
KrbFastArmoredRep ::= SEQUENCE {
- enc-fast-rep [1] EncryptedData, -- KrbFastResponse --
+ enc-fast-rep [1] EncryptedData, -- KrbFastResponse --
-- The encryption key is the armor key in the request, and
-- the key usage number is KEY_USAGE_FAST_REP.
...
}
KrbFastResponse ::= SEQUENCE {
- padata [1] SEQUENCE OF PA-DATA,
+ padata [1] SEQUENCE OF PA-DATA,
-- padata typed holes.
- finished [2] KrbFastFinished OPTIONAL,
+ finished [2] KrbFastFinished OPTIONAL,
-- MUST be present if the client is authenticated,
-- absent otherwise.
-- Typically this is present if and only if the containing
@@ -1942,28 +1814,28 @@ Appendix A. ASN.1 module
}
KrbFastFinished ::= SEQUENCE {
- timestamp [1] KerberosTime,
- usec [2] Microseconds,
+ timestamp [1] KerberosTime,
+ usec [2] Microseconds,
-- timestamp and usec represent the time on the KDC when
-- the reply was generated.
-Zhu & Hartman Expires September 6, 2007 [Page 32]
-
-Internet-Draft Kerberos Preauth Framework March 2007
+Zhu & Hartman Expires September 6, 2007 [Page 32]
+
+Internet-Draft Kerberos Preauth Framework March 2007
- rep-key-package [3] EncryptedData OPTIONAL,
+ rep-key-package [3] EncryptedData OPTIONAL,
-- EncryptionKey --
-- This, if present, replaces the reply key for AS and TGS.
-- The encryption key is the client key, unless otherwise
-- specified. The key usage number is
-- KEY_USAGE_FAST_FINISHED.
- crealm [4] Realm,
- cname [5] PrincipalName,
+ crealm [4] Realm,
+ cname [5] PrincipalName,
-- Contains the client realm and the client name.
- checksum [6] Checksum,
+ checksum [6] Checksum,
-- Checksum performed over all the messages in the
-- conversation, except the containing message.
-- The checksum key is the ticket session key of the reply
@@ -2005,9 +1877,9 @@ Authors' Addresses
-Zhu & Hartman Expires September 6, 2007 [Page 33]
-
-Internet-Draft Kerberos Preauth Framework March 2007
+Zhu & Hartman Expires September 6, 2007 [Page 33]
+
+Internet-Draft Kerberos Preauth Framework March 2007
Full Copyright Statement
@@ -2015,7 +1887,7 @@ Full Copyright Statement
Copyright (C) The IETF Trust (2007).
This document is subject to the rights, licenses and restrictions
- contained in BCP 78, and except as set forth therein, the authors
+ contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
@@ -2036,14 +1908,14 @@ Intellectual Property
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
- found in BCP 78 and BCP 79.
+ found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
- http://www.ietf.org/ipr.
+ http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
@@ -2061,12 +1933,6 @@ Acknowledgment
-Zhu & Hartman Expires September 6, 2007 [Page 34]
-
+Zhu & Hartman Expires September 6, 2007 [Page 34]
+
-
-